Step 2: Separate, then Wrap the Stems

Step 3: Keep Banana Slices Fresh

To prevent your banana slices from browning, you can use the same trick you've seen for apples: acid! Just toss your banana slices in some lemon juic...

For many people, purchasing a bunch of bananas is the ultimate act of hope in the face of experience.

I'm no different. My thinking generally goes, "If I buy these now, I'm set on breakfast for a week." Then Thursday comes around, my 'nanners have turned brown, and suddenly Friday's looking like a toaster waffle sort of day. Sometimes I consider baking banana bread and pretending I meant to let them get overripe, but mostly I throw them away and feel bad.

There is another way. A better way. A way that requires nothing more than what is already likely to be in your kitchen.

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Optional science!

We're looking specifically at enzymatic browning and the effect of ethylene production here. If you want to dig much deeper, there's a ton of academic research on bananas available online.

When fruits or vegetables are peeled or cut, enzymes contained in the plant cells are released. In the presence of oxygen from the air, the enzyme phenolase catalyses one step in the biochemical conversion of plant phenolic compounds to form brown pigments known as melanins. This reaction, called enzymatic browning, occurs readily at warm temperatures when the pH is between 5.0 and 7.0.
(Australian Institute of Food Science and Technology - PDF link.)

Ethylene promotes maturation and abscission of fruits. This has been known since early last century. Since 1934, it is known that plants themselves can produce ethylene. Many climacteric fruits such as apple, banana and tomato show a strong increase in ethylene levels at the late green or breaker stage. As a consequence of high ethylene chlorophyll is degraded and other pigments are being produced. This results in the typical color of the mature fruit peel. Activity of many maturation-related enzymes increases. Starch, organic acids and in some cases, such as avocado lipids, are mobilized and converted to sugars. Pectins, the main component of the middle lamella are degraded. The fruit softens. These metabolic activities are accompanied by a high respiration rate and consequently by high oxygen consumption. Ethylene levels are especially high in the separating tissues resulting in abscission of the fruit.
(Margret Sauter, University of Hamburg.)

This article seems to assume that all of the ethylene either comes out of the stalk to be absorbed by the banana, or enters in via the stalk. Isn't the ethylene generated by the banana itself, all over? How does wrapping up just the stalk affect anything?

I tried it to see if it would make any difference, and it was a resounding failure. I kept two bananas on my desk, about 9-12 inches apart (I briefly moved them closer for each photograph), one with stalk wrapped tightly with clingfilm (see fifth close-up photo) and one without. By the fourth day I don't think there is any significant difference between the two (or, in fact, on days 1, 2 or 3)!

Sorry for performing necromancy on this thread, but this bears stating: Ever since you tested and confirmed that wrapping the stem has no effect, I've wondered how I ever came to that conclusion. Well, I finally figured it out! I made an incorrect leap of imagination about ethylene production and abscission, the natural splitting of leaf or fruit from stem.

I re-read the Sauter paper and realized that I got a little too inferency. I thought that since ethylene caused abscission, it would make sense to cover the point prone to abscission. I didn't test when I saw confirmations from Lifehacker and eHow. (I know! Those were my sources after all the research I'd done?! I'm embarrassed for me, too.)

I think most bananas *are* "twins", in a sense, aren't they? Since the plants are all propagated by cloning another plant, and the fruit are unfertilised:

http://en.wikipedia.org/wiki/Bananas#Modern_cultivation

Maybe 'twins' isn't quite the right word but they all come from a relatively small number of "mothers" that have been cloned millions of times. This is probably why most bananas look very similar, unlike, say, apples.

Note that I should point out the photos above are in order on Day 1 (purchase day), Day 2, Day 3 and Day 4. I kept them separated by 9-12, apart from during their photoshoots, in case the ethylene from one banana affected the other.

From your results, it looks like separating the bananas followed by wrapping has no discernible visual effect. You busted my myth!

I tested separation but NOT wrapping. That was a bit of leap to synthesize the research around off-gassing and anecdotal reports that wrapping the stems made a difference. Clearly, it makes no aesthetic difference. (You mind if I incorporate your photos to make this ible more accurate?)

I'm surprised that nobody has suggested using green bags, such as Debbie Meyer Green Bags or Evert-Fresh Green Bags. These bags contain zeolite, which absorbs ethylene gas. They really do work well on all fruits and veggies that produce ethylene gas as a natural ripening process.

I separated 5 bananas, wrapped the stems in plastic wrap and placed them on a folded towel in the fridge. Altho the skins got dark, the fruit was perfect for eating and they'd been in there for 3 days. When I'd just set them on the counter, if the skins were dark the fruit was banana bread soft.

There's no such thing as an over-ripened banana. Bananas that are turning brown are perfect for using in recipes such as banana bread, banana cake, ice cream and so on. With that said, yes...separating bananas does keep them yellow longer. I haven't tried putting saran wrap on the stem...I'll have to do that.

I always had this problem and then one day I read that if you just cut off the stalk as low to the banana as possible without exposing the banana that the bananas would last much longer. This is what I did. Now I have bananas that last through the week and then some.

If you're inclined to buy too many bananas (no such thing!) and want to take a shot at winning the Scientific Method Contest that's running right now, documenting what actually happens over time with each freshness preservation method would probably vault you pretty high into the standings.

I tried this in a fashion. I happened to have melted wax in the kitchen for another project and dipped the stem ends. I didn't see any appreciable difference in aging, but I'll have to try it again sometime with more controls.

I'm very interested in seeing whether this method is replicable for more people. Let us know how your experiments go. So far the only clear winner for banana freshness preservation is separating them from the bunch.

Didn't read all 90 comments. Ignore this if it's already mentioned. Carbon dioxide is an inhibitor of ethylene production. To ensure longevity of bananas, put them in an airtight container connected to pressured carbon dioxide tank with flow control valve at the bottom of the container and a hole on top of the container to let go of ethylene. The only question is: can we afford it?

lt.greg... "I'm Chiquita banana and I've come to say - Bananas have to ripen in a certain way- When they are fleck'd with brown and have a golden hue - Bananas taste the best and are best for you - You can put them in a salad - You can put them in a pie-aye - Any way you want to eat them - It's impossible to beat them - But, bananas like the climate of the very, very tropical equator - So you should never put bananas in the refrigerator." -chiquita.com

Well "Chiki" - I guess I must have a magic refrigerator then - because when I put green bananas in there - they last three times as long as the ones from the same batch that I leave out on the counter. Yes - if you leave them in TOO LONG and don tr check them every few days they turn brown. But they DO definitely last longer for me, in my fridge. Greg :-)P

Listened to a review about a book written about the history of the modern banana not to long ago. Turns out that the old Chiquita banana jingle was intended to mislead you so that the fruit would go bad faster and you would have to buy more often. Good old capitalism and marketing at work.

Personally, I love bananas a little underripe so this is a great one for me. When the fruit does get a bit overripe peel them and put them in a freezer bag in the freezer & they'll be ready for making Banana Bread when you get the baking bug. I learned that at cooking school.

IMHO those seeming "overipe" nanners on the right are perfect for eating!! They won't be brown inside and now they actually taste like bananas. When they are eaten like on the left they have almost no flavor.

For those that don't know the more brown marks the banana has the better is for your health it come out some research short time ago related to that, it releases a compound TNF that helps the human body increasing is natural defenses.

You know what could be less trouble than using plastic wrap? getting those individual, latex finger cots! Though I suppose you'd have to get really small ones or have really thick stems on the bananas. Another alternative, if you frequently use candles, is to dip into molten wax.

@ djimdy - Pretty cool idea's there... the wax sparked a thought as in Canning wax, which I just so happened to have bought some at Publix a few months ago.

I was using it to wax the window slides in the house and used barely an edge of a bar by the time I was through with that project. I was wondering just what the heck I was going to do with all these bars of wax since I don't can anything at the moment. And I bring a couple bannanas to work each day... and I found keepting them in the fridge browns them real quick like ( I like to eat them cold).

A quick dip in the canning wax after seperating them might just do the trick.

another thing for overripe bananas: throw 2 or 3 of them in the blender, a cup and a half of soy milk, 4-5 ice cubes and 1-2 tablespoons of peanut butter. excellent peanut butter banana shakes for breakfast and way faster than banana bread!

Freeze the bananas first and use chocolate milk instead! We use chocolate almond milk, but I'm pretty sure soy exists too, and those smoothies are always gone fast. The little bit of peanut butter really does make all the difference.

Don't need to peel them - depending on your tolerance for food that looks (but doesn't taste) slightly slimy. Put them in the freezer peel and all, then pull them out and run hot water over the bananas in their peels until they feel slightly soft just under the skin. Crack one end (I find the stem end works better), open it just a little and squeeze out banana paste. Works great for banana bread (no need to mash), as well as for smoothies.

The ideas for keeping the bananas longer are very interesting - I'll have to try this. I have too many bananas in the freezer...

Personally, I've never had an over-ripe banana. They are best when they are completely yellow and covered in brown spots. That's when they are at their best, have the best taste and a kind of perfume about them. If there are too many ripe bananas to eat (as if!) I put them in the fridge then and get to them as soon as I can. They are definitely my favourite fruit.

When bananas get a bit too brown and I do tend to eat them riper then some people I chuck them in the freezer, they keep very well for what I use them for which is smoothies, They can be riper then a monkey would eat and still work great for this purpose.

Good simple ideas. I have heard that simply separating them will slow the ripening process. I separate mine and wrap a few in plastic and put in the fridge for later. The ones in the fridge the skin turns dark, but the flesh is firm for up to a week and nicely edible.

What most people don't realize is that putting them in the refrigerator causes the peeling to turn brown quicker but the bananas stay firm. It's just makes them look ugly. I've been doing this for years and the bananas are just right.

I'm pretty sure that bananas have already been stored at refrigerator temperatures at the packing house. That is at least true for other fruits and vegetables. In a typical home refer, there are other environmental characteristics than just low temp. It's pretty dry in there, too.

Have you ever done that before? I try to only give advice when I've tried it myself or know for a fact that it works. In this case, I've tried it twice and the other two replies to you are right--putting bananas in the refrigerator makes them ripen and then rot faster. It was either the Stuff You Should know podcast or the Naked Scientists podcast that explain the specifics as to why this happens. If memory serves, the cold actually causes damage to the banana.

@ uberlazy - actually I put mine in the fridge - less this process of wrapping the stem. Which I will be trying with the Bananas I get tonight.

What I found is that by putting them in the fridge - they do not rippen faster - they just turn brown fast - real fast. But stay as ripe as the day I bought them.

That mentioned I wrapped them as a whole - (not just the stem part) and I've had them loose in the fridge - both ways - wrapped whole or just loose the same result happened. the skin browned fast but the banna itself did not rippen further.

I'm going to try this instructable on some new bananas tonight... see what happens.

I may have to use this method and put only the bananas i want to take to lunch the next day in the fridge the night before... not sure yet.

@wilgubeast; A timely topic for me, thank you! Tweeted, and will try the individual stem wrapping technique. @batkinson1; Great tip to check out Chiquita.com. @thegreat refrigeratordebate: "You can slow down the banana ripening process by storing the fruit in the refrigerator. The skin may darken, but the banana will be just right for several days." (chiquita.com, banana information page)

I always put overly ripe or just ripe bananas in the freezer, and then when nice and hard, I peel them, slice them (even frozen they still slice), then put them in a food processor, and blend them up with some half+half or whipping cream (small amount, like 1/2 C.), and it turns them into a smooth banana flavored ice cream. They are already very sweet, so you don't even need sugar, unless you have a super sweet tooth. Smooth like ice cream, delicious, and a fraction of the calories of ice cream.

Hey thanx for posting this tip! I knew about lettuce and other veggies and fruit and the process you mention in your instructable about the cause of spoilage. But could figure out why my wrapping process wasn't working.

Now I know, the culprate is the stem not the whole banana.

I'll will be trying this tonight on some new bananas I'll be buying tonight for lunches this coming week!

The most recent issue of Cook's Magazine states that they tested 1- 2 Tablespoons Honey diluted in 1 Cup water as a substitute for the traditional Lemon Juice or Lemon Juice/water to keep fruits from browning with excellent result. I would imagine this would work for Banana Slices as well (?). I haven't tried it yet, but I often find the lemon residue less palatable...honey would be a natural sweetener as well. Thanks for your research into the never-ending quest for keeping bananas from over-ripening too soon!

I agree about the flavor improvement but of course there is such a thing as "over-ripe" bananas - just give them another month or two and they will be "over-ripe" for you too. Once they start dripping I give up on them.